The invention relates to a photomask used in an exposure process for fabricating a semiconductor device and a method of fabricating the same.
In general, a semiconductor device is realized through various patterns on a wafer, and these patterns are formed using a photolithography process. According to a conventional photolithography process, a photoresist layer is formed on a layer to be patterned on a wafer and a predetermined portion is exposed using a photomask. Next, a photoresist layer pattern that exposes some of a surface of the layer to be patterned is formed by removing a portion of the photoresist layer, the solubility of which is changed or unchanged by the exposure, in a development process using a developing solution. Then, a pattern is formed by removing the exposed portion of the layer to be patterned by etching using the photoresist layer pattern as an etch mask. In this procedure, the pattern formed on the wafer is defined by the photoresist layer pattern and the photoresist layer pattern is formed as the pattern on the photomask is transferred thereto. Therefore, the pattern on the photomask layer is consequently transferred to the pattern on the wafer.
However, as the degree of integration of semiconductor devices increases, the sizes of pattern of photomasks are also gradually becoming miniaturized. Due to this tendency, various problems may be generated in the procedure of forming fine patterns of a photomask pattern. One of the typical problems is a pattern critical dimension (CD) error by which the pattern size of the photomask is not accurately formed. This pattern CD error may be generated by an exposure apparatus or in a procedure of performing the exposure process. When this pattern CD error is generated, the photoresist layer pattern to which the pattern of the photomask is transferred is not formed to a desired size and, consequently, the pattern on the wafer is also not formed to a desired shape.